Polymeric shell adherently supported by a liner and a method of manufacture

ABSTRACT

An article comprising at least one cured, liquid-impervious polymeric shell substantially free from defects, at least one liner, and a non-tacky, thermoplastic adhesive layer between the shell and the liner, wherein the adhesive layer is melted and solidified to create a non-tacky bond between the shell and the liner, which can be moisture-absorbing or cut-resistant, whereby the liner supports and limits stretch ability of the shell, thereby preventing adhesive delamination between the adhesive layer and either of the shell and/or the liner; a method for the manufacture of an article comprising a supported, polymeric shell, such as a glove, a gauntlet, an apron, or a boot, comprising providing a cured, liquid-impervious, polymeric shell, providing a knitted/woven liner, incorporating a non-tacky, thermoplastic adhesive layer between the shell and the liner, such as by hot-melt spraying, dry-powder spraying or fiber-coating, creating intimate contact between the shell, the adhesive layer, and the liner, subjecting the shell, the adhesive layer, and the liner to infrared radiation to melt the adhesive layer and create a bond between the shell and the liner, and cooling the shell; as well as other methods.

This application claims the benefit of U.S. provisional patentapplication No. 60/614,604, filed on Sep. 30, 2004.

TECHNICAL FIELD OF THE INVENTION

This invention relates to a polymeric shell, which is supported by anadhesively bonded liner, thereby limiting the stretch of the polymericshell, and a method of making same.

BACKGROUND OF THE INVENTION

Polymeric shells, including unsupported medical, surgical and othergloves, are typically made of latex. These polymeric shells are producedin an assembly line fashion by dipping a coagulant-coated former ofdesired shape into an aqueous latex emulsion, thereby gelling the latexand subsequently curing the gelled layer to form the polymeric shell.The aqueous latex emulsion may comprise additives, including viscositymodifiers, waxes, surfactants, stabilizers, cross-linking agents and thelike, to produce a cured latex product having specific characteristics,such as thickness, tensile strength, tear and penetration resistance,flexibility; etc., in a controlled manner. Aqueous latexes of differentcompositions are known in the art, and they include natural rubberlatexes, synthetic polyisoprenes, and other synthetic latexes, includingneoprene, nitrile compositions, and the like. Typical examples ofpolymeric shells made from the aqueous dipping process are described inU.S. Pat. No. 3,268,647 to Hayes et al., which discloses the manufactureof rubber gloves.

Polymeric shells with a supported liner are known in the art and aretypically used in applications that require a strong latex productcommonly used in industrial environments, such as gloves, for protectinghands. A number of patents disclose coating the liner with a latexcomposition. For example, U.S. Pat. No. 2,083,684 to Burke disclosesrubber-coated gloves and a method of making the same. U.S. Pat. Nos.4,514,460, 4,515,851, 4,555,813, and 4,589,940 to Johnson discloseslip-resistant gloves and a method for their manufacture. U.S. Pat. No.5,070,540 to Bettcher et al. discloses a protective garment. A metallicwire core and two fiber strand wrappings are coated by dipping in anitrile rubber composition. U.S. Pat. No. 5,581,812 to Krocheskidiscloses a leak-proof textile glove. The inner surface of acut-resistant textile layer is bonded to a leak-proof,petroleum-resistant, polymeric material, such as PVC, without anintervening adhesive layer, since the leak-proof polymeric material isapplied to a liner placed on a former. U.S. Pat. No. 5,822,791 to Barisdiscloses a protective material and a method wherein a cut-resistant,protective layer is coated with an impervious elastomeric material. Atypical process for producing these supported gloves includes the use ofa liner, which is dressed over a former, optionally treated with acoagulant, and dipped into an aqueous latex emulsion to form a gelledlatex layer over the liner, which is then cured. The penetration of theaqueous latex emulsion into the dressed liner results in‘strike-through,’ or “penetration,” which creates an unsightlyappearance of the supported product and makes the article more rigid andless flexible. A number of steps are taken to minimize ‘strike-through,’including coagulant coating of the liner as a blocking agent, andincreasing the viscosity of the aqueous latex emulsion to prevent thepenetration of the aqueous emulsion into the liner; etc. The aqueouslatex emulsion used may comprise several additives, such as stabilizers,foaming agents, cross-linking agents, waxes, and surfactants. The latexcomposition may be natural rubber, polyisoprene, neoprene, or nitrilerubber; etc. These supported polymeric shell products provide sufficientprotection to the hands of the wearer. The dipping and drying of a gloveformer in a latex emulsion to form a glove is disclosed. However, thechemical resistance of the polymeric shell is generally inadequate dueto poor coverage of the latex emulsion over the liner and may have holesin the latex layer where the fibers of the liner cross. A further andperhaps more serious consequence of coating over a knitted fabric is thepossibility that the resultant polymeric film is compromised, resultingin a non-uniform thickness, which may compromise the chemical-resistantbarrier of the film in parts or which may not be liquid-proof. This isdue to the potential of surface fibers passing into or through thecoating, hence providing an easier path for liquids to pass or permeatethrough the polymeric film. Foamed latex layers may have interconnectedporosity, which also may provide decreased chemical resistance to thesupported polymeric shell latex article.

U.S. Pat. No. 4,283,244 to Hashmi discloses a method of makingfabric-lined articles. This method of making a lined elastomeric articlecomprises the steps of applying a coating of adhesive in a liquid stateto an elastomeric article on a form, drying the adhesive on the articleto form a pressure-sensitive adhesive coating, treating the adhesivecoating with a lubricant, and thereafter applying a preformed liningover the article and the adhesive coating to connect adhesively thelining to the elastomeric article. The elastomeric article is a latexproduct produced by dipping a coagulant-treated former into an aqueouslatex emulsion and drying and curing the elastomeric article on theformer. The adhesive is 68096-01 resin supplied by Evans Adhesives ofColumbus, Ohio, suspended in water. The elastomeric article on theformer is dipped in the adhesive, dried to form a pressure-sensitiveadhesive coating, lubricated, and dressed with a liner. The linedelastomeric article is removed from the former and turned inside-out.Unfortunately, the sweating action combined with body temperatureresults in the extraction or dissolution of the adhesive, producing anunpleasant skin feel. The adhesive also is soft, has low strengthproperties, and stays tacky even after drying.

U.S. Pat. No. 4,918,754 to Leatherman et al. discloses a flocked gloveand a plastic sleeve member bonded thereto. A preformed, flock-lined,rubber-like glove has its cuff folded back to expose the flocked lining,is mounted in a rotating support, and is sprayed with a hot-meltadhesive on the flock-lined, folded cuff. The glove is telescoped onto apolyethylene sleeve, and the adhesive is melted by high frequencyheating to bond the polyethylene sleeve with the cuff. The adhesivebonds the polyethylene sleeve to the cuff portion of the glove and doesnot bond the entire polymeric shell with a liner.

U.S. Pat. Nos. 5,599,895, 5,618,904, and 5,932,680 disclosemoisture-curing polyurethane hot-melt adhesive. The hot-melt adhesiveincludes at least one polyurethane prepolymer of at least onepolyisocyanate, toluene diisocyanate, and/or MDI, at least onepolyalkylene glycol, at least one polyester glycol, and optionaladditives, such as a stabilizer, particularly toluenesulfonylisocyanate.

U.S. Pat. Nos. 6,543,059 and 6,596,345 to Szczesuil et al. disclose aprotective glove and a method for making same. This protective glove fora human hand includes an inner glove of polyester, non-woven,needle-punched material and a melt-sprayed polyurethane coating. Thisnon-woven needle punched material has no mechanical integrity, unlike awoven or knitted fabric, and the hot-melt-sprayed polyurethane adhesiveholds the configuration together, forming a glove. The melt-sprayedglove is heated to a temperature of 300 to 325° F. to allow the remeltedpolyurethane to penetrate the inner glove to a depth short ofpenetrating to the inner surface of the inner glove. The polyurethanecoating on the outer surface of the inner glove cures in approximately24 hours by reaction with ambient moisture. The inner glove is furthercoated with a rubberized material to produce an inner glove heldtogether by the rubber, which is then cut into pieces and sewn to form aglove with internal sewn seams. Such a glove is not liquid-impervious,since these sewn seams are not bonded and leak and, therefore, notchemically resistant. The protective glove is said to protect frompuncture.

U.S. Pat. No. 6,539,552 to Yoshida discloses a flexible waterproofglove. This waterproof glove is formed of a flexible inner glove body ofa base fabric that is thermally bonded with a low-melting, thermalplastic resin film and a flexible outer glove body of the same fabric.The thermal bonding of the inner glove with the outer glove isaccomplished by heating the glove to melt the low-melting, thermalplastic resin film, which has a lower melting point than that of thebase fabric. The melted thermal plastic resin film results in awatertight glove. In one embodiment, the thumb portion of the glove ismanufactured separately and bonded to the rest of the glove to provideimproved thumb movement. The molten and solidified polymer thermallybonded to the inner and outer glove body results in a watertight glove.The overall rigidity and resistance to movement of the glove isaddressed by the separate attachment of the thumb component to theglove. There is no latex or polymeric shell in this glove. Thus, thisglove has no stretch characteristics resembling those that are commonlyavailable in a latex-based glove product.

Therefore, there is a strong need in the art for a supported, chemicallyresistant, polymeric shell, latex article that effectively managesmoisture, such as sweat, and exposure to body temperature. The linerprovides stretch resistance, a comfortable feel, moisture (e.g., sweat)management, and cut-resistance as desired, while the polymeric shellprovides chemical resistance. There is also a need in the art for amanufacturing process that produces a supported, polymeric shell, latexarticle in a production environment. A more efficient method foradhering a liner to a polymeric shell is needed. Additionally, a methodis needed that substantially minimizes, and preferably eliminates,strike-through, i.e., penetration of a latex composition into the liner.Further, a method is needed that will insure the physical integrity ofthe polymeric shell, i.e., no thin or weak areas or holes, thusproviding a sound liquid-proof barrier. It is an object of the presentinvention to provide such a method. It is another object of the presentinvention to provide an article comprising a polymeric shell, anadhesive, and a liner, and having physical integrity taking advantage ofthe unique properties of the liner and that of a chemically resistantliquid-proof polymeric shell. These and other objects and advantages, aswell as additional inventive features, will be apparent from thedetailed description provided herein.

BRIEF SUMMARY OF THE INVENTION

The present invention provides an article comprising at least one cured,liquid-impervious polymeric shell substantially free from defects; atleast one liner; and a non-tacky, thermoplastic adhesive layer placedbetween the at least one shell and the at least one liner. The adhesivelayer is applied to either the liner or the polymeric shell, melted andsolidified to create a non-tacky bond between the at least one shell andthe at least one liner. The liner supports and limits stretch ability ofthe shell, thereby preventing adhesive delamination from either theshell and/or the liner.

The present invention further provides a method for the manufacture ofan article comprising a supported, polymeric shell. The method comprisesproviding a cured, liquid-impervious, polymeric shell produced bydipping a coagulant-coated former into an aqueous latex emulsion,gelling a latex layer on the former, and heating the gelled latex layeron the former to crosslink and cure the latex layer. The method furthercomprises providing a liner knitted or woven using fibers selected fromthe group consisting of cotton, rayon, polyester, polypropylene,Kevlar™, Spectra™, steel wire, or a combination thereof, placing thepolymeric shell over a skeletal support, coating the external surface ofthe polymeric shell with a non-tacky, thermoplastic adhesive layer,dressing the shell with the liner such that the adhesive layer isbetween the polymeric shell and the liner; inflating the polymeric shellwith air pressure to create intimate contact between the polymericshell, the adhesive layer, and the liner, subjecting the polymeric shellwith the adhesive layer and the dressed liner to infrared radiation,thereby melting the adhesive layer and creating a bond between thepolymeric shell and the liner, and cooling the polymeric shell with theadhesive layer and the liner to create the supported, polymeric shellarticle.

Another method of manufacture is also provided. The method comprisesproviding a cured, liquid-impervious, polymeric shell produced asdescribed above, providing a liner knitted or woven as described above,placing the liner over a former, coating the external surface of theliner with a non-tacky, thermoplastic adhesive layer, stripping theadhesive layer-coated liner from the former, placing the polymeric shellover a skeletal support, dressing the polymeric shell with the adhesivelayer-coated liner in such a manner that the adhesive layer is betweenthe shell and the liner, and inflating the polymeric shell, subjectingthe shell to infrared radiation, and cooling the shell as describedabove.

Yet another method of manufacture is provided. The method comprisesproviding a liquid-impervious polymeric shell produced as describedabove, coating fibers with a non-tacky, thermoplastic adhesive,providing a liner knitted or woven using the fibers coated withadhesive, placing the polymeric shell over a skeletal support, dressingthe polymeric shell with the liner, and inflating the polymeric shell,subjecting the shell to infrared radiation, and cooling the shell asdescribed above.

Still yet another method of manufacture is provided. The methodcomprises providing first and second liquid-impervious polymeric shellsproduced as described above, stripping the first and second polymericshells from the formers, placing the first polymeric shell over askeletal support, coating the external surface of the first polymericshell with a first non-tacky, thermoplastic adhesive layer, providing acut-resistant liner knitted or woven using fibers such as Kevlar™,Spectra™ or steel wire as described above, dressing the first polymericshell with the cut-resistant liner such that the adhesive layer isbetween the polymeric shell and the liner, coating the external surfaceof the cut-resistant liner with a second non-tacky thermoplasticadhesive layer, dressing the first shell with the adhesive layer-coatedliner with the second shell, and inflating the shell, subjecting theshells to infrared radiation, and cooling the shells as described above.

Even still yet another method of manufacture is provided. The methodcomprises providing first and second liquid-impervious polymeric shellsproduced as described above, stripping the first and second polymericshells from the formers, providing a cut-resistant liner knitted orwoven using fibers as described above, applying a thermoplastic adhesiveto the inner and outer surfaces of the liner by hot-melt or dry-powderspraying, placing the first shell over a skeletal support, dressing thefirst polymeric shell with the adhesive-coated liner, dressing the firstpolymeric shell with the adhesive-coated liner with the second polymericshell, and inflating the polymeric shells, subjecting the shells toinfrared radiation, and cooling the polymeric shells as described above.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates a fragmentary cross-sectional view of a polymericshell latex article supported by a liner that is bonded on the inside ofthe polymeric shell by an adhesive layer in accordance with the presentinvention.

FIG. 1B illustrates a fragmentary cross-sectional view of a polymericshell latex article supported by a cut-resistant liner that is bonded onthe outside of the polymeric shell with an adhesive layer in accordancewith the present invention.

FIG. 1C illustrates a fragmentary cross-sectional view of a polymericshell latex article supported by a cut-resistant liner bonded to theoutside of the polymeric shell by an adhesive layer and amoisture-management liner bonded to the interior surface of thepolymeric shell by an adhesive layer in accordance with the presentinvention.

FIG. 1D illustrates a fragmentary cross-sectional view of a polymericshell latex article with two polymeric shells supported by acut-resistant liner bonded there between by adhesive layers inaccordance with the present invention.

FIG. 2A illustrates a front elevational view of a skeletal mandrel forattaching a polymeric shell and means for inflating the polymeric shellin accordance with the method of the present invention.

FIG. 2B illustrates an assembly of the skeletal mandrel of FIG. 2Aincluding a polymeric shell and a liner with an adhesive layer therebetween depicted in broken-line.

FIG. 2C illustrates a side elevational view of the assembly of FIG. 2B.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides an article comprising at least one cured,liquid-impervious polymeric shell substantially free from defects, atleast one liner, and a non-tacky, thermoplastic adhesive layer placedbetween the at least one polymeric shell and the at least one liner. Theadhesive layer is melted and solidified to create a non-tacky bondbetween the at least one polymeric shell and the at least one liner. Theliner supports the shell and limits stretch ability of the polymericshell to that of the liner, thereby limiting stress at the polymericshell-adhesive layer interface and at the adhesive layer-liner interfaceand preventing adhesive delamination at the interfaces. The adhesivelayer is immune to leaching or extraction by moisture or sweat at bodytemperature.

The polymeric shell needs to be liquid-impermeable so that the resultantarticle is chemically resistant. The polymeric shell can comprisenatural and/or synthetic latex, such as nitrile latex, styrene butadienerubber (SBR), and other standard latex variants. The polymeric shelltypically stretches from about 50-500%, whereas a woven textile linerstretches, depending on fiber geometry, from about 0.5-5%, and a knittedliner stretches from about 5-20%.

The polymeric shell can be prepared by any suitable method, includingevaporation of a thin layer of polymer dissolved in a solvent orgelation of an aqueous latex emulsion over a coagulant-coated former.Gelation over a coagulant-coated former is preferred. In the preferredmethod an aqueous latex composition of natural latex or a syntheticlatex composition comprising polyisoprene, nitrile, neoprene, and thelike, is gelled and later cured on a coagulant-coated former to producea liquid-impervious polymeric shell. The most commonly employed methodof manufacturing the polymeric shell is to dip a coagulant-coated formerin the shape of the desired article in an aqueous latex emulsion to gela latex layer over the formed surface and to heat the gelled latex to atemperature that cross-links and cures the latex layer. Since the gelledlatex layer is produced over the smooth surface of the former with noliner there between, a substantially defect-free liquid imperviouspolymeric shell is produced.

The liner can comprise a woven textile fabric or a knitted textilefabric. The liner can comprise cotton, rayon, polyester, polypropylene,Kevlar™ (DuPont, Wilmington, Del.), Spectra™ (Honeywell, Morristown,N.J.), steel wire, or any combination of two or more of the foregoing. Aliner comprising cotton and/or rayon, for example, can be placed on theskin-contacting surface of the article, thereby providing a comfortablefeel and moisture-absorption. A liner comprising steel wire, Kevlar™,and/or Spectra™, can be placed on the exterior surface of the article orbetween two polymeric shell layers of an article, thereby providingcut-resistance. Such liners can be used in combination.

There are several key characteristics needed for the adhesive layer tocreate a satisfactory bond between the polymeric shell and the liner.First, the adhesive composition must be non-tacky so that the liner orshell can be dressed one over the other. Second, the adhesivecomposition must be a thermoplastic polymer, which melts readily at atemperature that is sufficiently low so that it can be re-melted duringthe bonding process without damaging the shell or the liner. On theother hand, the thermoplastic polymer must melt at a temperature that issufficiently high so that it is not affected by body temperature or thetemperature of conditions of use. In addition, the adhesive layerpreferably resists moisture and sweat so that the adhesive layer is notextracted and the skin is not irritated. Any polymer that is non-tackyat ambient temperature but can be melted at a temperature that does notdegrade the shell or the liner can be used. The adhesive layer cancomprise a polymer selected from the group consisting of low molecularweight polyethylene, polyester, ethyl vinyl acetate, ethylene 2-ethylhexyl acrylate polymer, and polyurethane, and has a melting point ofless than about 140° C. Polyurethane is preferred. The adhesive maycontain a thermosetting component, which allows the adhesive to hardendue to reactions therein. An example of a suitable adhesive ispolyurethane with isocyanate, such as grade 35-503, which is availablefrom Sovereign Specialty Chemicals (Chicago, Ill.), or 3M Jet-weld™ (St.Paul, Minn.), which causes cross-linking of the adhesive upon exposureto moisture. The strength of the bond increases as a function of time ofexposure to moisture, until all of the cross-linking agent is exhausted.The adhesive is preferably applied in an amount in the range of about0.001-0.01 g/cm².

The polymeric shell, the liner, and the adhesive layer have differentstretching characteristics. When a fixed load is applied to a material,the applied stress level is the applied load divided by thecross-sectional area. The material has a strain, which is the appliedstress divided by the modulus of elasticity of the material, providingthe stretch ability of the material for the simple stress state of puretension. When the polymeric shell, adhesive layer, and liner are joinedtogether and a load is applied, the strain in all of these threeelements is equal, unless they separate at their interfaces. Because theleast stretchable member primarily carries the load, the moststretchable member is supported from stretching. In the context of thepresent invention, the polymeric shell is most stretchable and issupported by the liner, which is the least stretchable element. Theadhesive layer serves to transfer the load from the polymeric shell tothe liner. There are two methods by which the polymeric shell issupported by the liner. In the first method, the stretch ability of theadhesive layer is less than that of the polymeric shell but greater thanthat of the supporting liner. In this case, the polymeric shell and thesupporting liner are intimately bonded to the adhesive layer, and theoverall stretch of the supported polymeric shell is closer to that ofthe stretch ability of the supporting liner. In the second method, theadhesive layer has a stretch ability closer to that of the polymericshell, and the penetration of the adhesive into the interstices of theknitted or woven fabric is relied on to transfer the load to thesupporting liner from the polymeric shell.

Typical polymeric shells stretch from about 50-500%, whereas the linerstretches from about 0.5-20%, depending on how the fibers are packed.For example, if the liner is woven, stretch ability is limited by thesize of the fiber used and the spacing between the fibers. When thewoven liner is stretched, it can only stretch until the fibers contacteach other. A woven liner with tight fiber packing has a very limitedstretch ability, which may be in the range of about 0.5-5%. A knittedliner, on the other hand, is more stretchable and can stretch from about5-20%. The adhesive layer generally has different mechanicalcharacteristics from those of the shell or the liner. If the adhesivelayer has low stretch ability and is applied only to the polymericshell, the stretching of the polymeric shell will result in delaminationat the polymeric shell-adhesive layer interface. This is due to thehigher modulus of elasticity and reduced stretch ability of the adhesivelayer, which may stretch about 10-100% as compared to the polymericshell, which typically stretches about 50-500%. The only way to preventthe delamination or physical separation of the polymeric shell from theadhesive layer is to prevent the stretching of the polymeric shell. Thisis successfully accomplished by bonding the side of the adhesive layer,which is opposed to the side of the adhesive layer bonding to thepolymeric shell, to a liner having sufficient mechanical integrity. Theresulting composite does not stretch very much, i.e., more like theliner than the shell. When the adhesive layer stretches about 100-600%,such as when the adhesive is moisture-curing polyurethane, nodelamination occurs at the polymeric shell-adhesive layer interface. Inthis case, successful load transfer to the liner is achieved by allowingthe adhesive to penetrate the spaces between the fibers in theknitted/woven liner, thereby causing peg-like bonding. Depending oncomposition and the method employed to coat the adhesive layer to asubstrate, i.e., shell or liner, the adhesive layer stretches from about10-600%. Preferably, the method employed to coat the adhesive layer tothe substrate ensures load transfer from the shell to the liner by theadhesive layer. When the adhesive layer stretches from about 100-600%,the adhesive needs to penetrate between the knitted/woven fibers of theliner to a provide a peg-like bond. When the adhesive layer stretchesfrom about 10-100%, penetration of the adhesive layer into the liner isnot necessary.

A number of thermoplastic adhesive systems are available that stretchfrom about 10-100%. These include low molecular weight polyethylene(mp=110° C.), polyester (mp=120° C.), ethylene vinyl acetate (mp=121°C.), ethylene 2-ethyl hexyl acrylate polymer, EEHA (mp=125° C.), andthermoplastic polyurethane, such as RTP-2300 A (mp=111° C.) from RTPCo., Winona, Minn. These polymers can be sprayed as a molten liquid andsolidify as a non-tacky layer suitable for use in the context of thepresent invention.

Alternatively, the adhesive layer can comprise a moisture-cured,cross-linking polyurethane, which can be sprayed as a liquid and whichstretches from about 500-600%, and does not separate from the polymericshell. For example, 3M Jet-weld™ can be sprayed at 121° C. as a jet andcures and cross-links by reaction with moisture. Another example ispolyurethane with isocyanate, such as grade 35-503, which is availablefrom Sovereign Specialty Chemicals. When a polymeric shell is adhered toa liner with a moisture-cured, thermoplastic polyurethane adhesive, theliner breaks to pieces without separation at the shell-adhesive layerinterface or at the adhesive-liner interface indicating complete loadtransfer to the liner to such an extent that complete disintegration ofthe liner results. Thus, a moisture-cured, thermoplastic polyurethaneadhesive is preferred.

Since the polymeric shell is made from a standard conventional dipping,gelation, and curing process, it can be produced at the same location ina continuous process production line or removed from storage just priorto the liner/adhesive bonding operation. As a matter of fact, thephysical location of the polymeric shell manufacturing plant can beseparated from the liner adhesive bonding process facility. Due to thisspatial and temporal capability, the production process for a supportedpolymeric shell product can be “just in time” according to ordersreceived, thereby providing improved cost structure.

The polymeric shell can be coated with the non-tacky adhesive layer andbonded to a liner. In this case, the polymeric shell is placed over aformer, coated with the non-tacky thermoplastic adhesive layer, andcooled to ambient temperature. Then, a liner is dressed over theadhesive layer-coated polymeric shell and heated to melt the adhesivelayer. When the polymeric shell is removed from the former and inverted,the liner is on the interior surface of the polymeric shell. In apreferred embodiment, the polymeric shell can be supported by a skeletalshell, coated with a non-tacky adhesive layer, and dressed with a liner.The polymeric shell supported by the skeletal former is inflated toallow intimate contact between the polymeric shell and the liner andsubjected to infrared heat to melt the adhesive layer. The polymericarticle is inverted so that the liner is inside the polymeric shell. Theliner, again, limits the stretch ability of the polymeric shell.

Accordingly, in view of the above, the method can comprise the steps of:

-   -   a) providing a cured, liquid-impervious, polymeric shell        produced by dipping a coagulant-coated former into an aqueous        latex emulsion, gelling a latex layer on the former, and heating        the gelled latex layer on the former to crosslink and cure the        latex layer;    -   b) providing a liner knitted or woven using fibers selected from        the group consisting of cotton, rayon, polyester, polypropylene,        Kevlar™, Spectra™, steel wire, or a combination thereof;    -   c) placing the shell over a skeletal support;    -   d) coating the external surface of the shell on the skeletal        support with a non-tacky, thermoplastic adhesive layer;    -   e) dressing the shell with the liner such that the adhesive        layer is between the shell and the liner;    -   f) inflating the shell placed over the skeletal support with air        pressure to create intimate contact between the polymeric shell,        the adhesive layer, and the liner;    -   g) subjecting the shell with the adhesive layer and the dressed        liner to infrared radiation, thereby melting the adhesive layer        and creating a bond between the shell and the liner; and    -   h) cooling the shell with the adhesive layer and the liner to        create the supported, polymeric shell. The liner can comprise        cotton, rayon, or a combination thereof such that, when the        shell is inverted, a moisture-absorbing article is produced.        Alternatively, the liner can comprise Kevlar™, Spectra™, steel        wire, or a combination thereof, such that the shell produces a        cut-resistant article. The adhesive layer can be coated on the        external surface of the shell on the skeletal support by        hot-melt spraying or dry-powder spraying.

Alternatively, the liner can be coated with the non-tacky adhesive layerand bonded to a polymeric shell. In this case, the polymeric shell isplaced over a former, and the liner is coated with the non-tackythermoplastic adhesive layer. The adhesive layer-coated liner is dressedover the polymeric shell and heated to melt the adhesive layer. Theliner is then bonded to the exterior of the polymeric shell. In apreferred embodiment, the polymeric shell is supported by a skeletalshell and dressed with an adhesive layer-coated liner, such that theadhesive layer is between the polymeric shell and the liner. Theassembly is then heated to melt the adhesive layer, thereby creating abond between the polymeric shell and the liner.

Accordingly, in view of the above, the method can comprise the steps of:

-   -   a) providing a cured, liquid-impervious, polymeric shell        produced by dipping a coagulant-coated former into an aqueous        latex emulsion, gelling a latex layer on the former, and heating        the gelled latex layer on the former to crosslink and cure the        latex layer;    -   b) providing a liner knitted or woven using fibers selected from        cotton, rayon, polyester, polypropylene, Kevlar™, Spectra™,        steel wire, or a combination thereof;    -   c) placing the liner over a former;    -   d) coating the external surface of the liner on the former with        a non-tacky, thermoplastic adhesive layer;    -   e) stripping the adhesive layer-coated liner from the former;    -   f) placing the shell over a skeletal support;    -   g) dressing the shell with the adhesive layer-coated liner in        such a manner that the adhesive layer is between the shell and        the liner;    -   h) inflating the shell placed over the skeletal support with air        pressure to create intimate contact between the polymeric shell,        the adhesive layer, and the liner;    -   i) subjecting the shell with the adhesive layer and the liner to        infrared radiation, thereby melting the adhesive layer and        creating a bond between the shell and the liner; and    -   j) cooling the shell with the adhesive layer and the liner to        create the supported, polymeric shell article. The liner can        comprise cotton, rayon, polyester, polypropylene, or a        combination thereof such that, when the supported polymeric        shell is inverted, a moisture-absorbing article is produced.        Alternatively, the liner can comprise Kevlar™, Spectra™, steel        wire, or a combination thereof, such that the supported        polymeric shell produces a cut-resistant article. The adhesive        layer can be coated on the external surface of the liner on the        former by hot-melt spraying or dry-powder spraying.

Alternatively, the fibers used to knit or weave the liner can be coatedwith the non-tacky thermoplastic adhesive prior to weaving or knitting.In this embodiment, the method can comprise the steps of:

-   -   a) providing a cured, liquid-impervious polymeric shell produced        by dipping a coagulant-coated former into an aqueous latex        emulsion, gelling a latex layer on the former, and heating the        gelled latex layer on the former to crosslink and cure the latex        layer;    -   b) coating fibers selected from cotton, rayon, polyester,        polypropylene, Kevlar™, Spectra™, steel wire, or a combination        thereof with a non-tacky, thermoplastic adhesive;    -   c) providing a liner knitted or woven liner using the fibers        coated with adhesive;    -   d) placing the shell over a skeletal support;    -   e) dressing the shell with the liner;    -   f) inflating the shell placed over the skeletal support with air        pressure to create intimate contact between the liner, the        thermoplastic adhesive, and the shell;    -   g) subjecting the shell, the liner, and the thermoplastic        adhesive to infrared radiation, thereby melting the adhesive and        creating a bond between the shell and the liner; and    -   h) cooling the shell with the adhesive and the liner to create        the supported, polymeric shell article. The liner can comprise        cotton, rayon, or a combination thereof such that, when the        shell is inverted, a moisture-absorbing article is produced.        Alternatively, the liner can comprise Kevlar™, Spectra™, steel        wire, or a combination thereof such that the shell produces a        cut-resistant article.

In yet another embodiment, the method can comprise the steps of:

-   -   a) providing first and second cured, liquid-impervious polymeric        shells by separately dipping two coagulant-coated formers into        an aqueous latex emulsion, gelling a latex layer on each of the        two formers, heating the gelled latex layers on the formers to        crosslink and cure the latex layers, and stripping the cured        first and second polymeric shells from the formers;    -   b) placing the first polymeric shell over a skeletal support;    -   c) coating the external surface of the first polymeric shell on        the skeletal former with a first non-tacky, thermoplastic        adhesive layer;    -   d) providing a cut-resistant liner knitted or woven using fibers        selected from Kevlar™, Spectra™, steel wire, or a combination        thereof;    -   e) dressing the first polymeric shell with the adhesive        layer-coated cut-resistant liner such that the adhesive layer is        between the first shell and the liner;    -   f) coating the external surface of the cut-resistant liner with        a second non-tacky thermoplastic adhesive layer;    -   g) dressing first shell with the adhesive layer-coated liner,        with the second shell;    -   h) inflating the first shell placed over the skeletal support        with air pressure to create intimate contact between the first        shell, the first adhesive layer, the cut-resistant liner, the        second adhesive layer and the second shell;    -   i) subjecting the first shell, the first adhesive layer, the        cut-resistant liner, the second adhesive layer, and the second        shell to infrared radiation, thereby melting the adhesive layer        and creating a bond between the first shell, the cut-resistant        liner, and the second shell;    -   j) cooling the shells bonded with adhesive layers to create the        cut-resistant, supported polymeric shell article; and    -   k) optionally coating the external surface of the cut-resistant        liner with a flexible polymeric layer.

In still yet another embodiment, the method can comprise the steps of:

-   -   a) providing first and second cured, liquid-impervious polymeric        shells by separately dipping two coagulant-coated formers into        an aqueous latex emulsion, gelling a latex layer on each of the        two formers, heating the gelled latex layers on the formers to        crosslink and cure the latex layers, and stripping the cured        first and second polymeric shells from the formers;    -   b) providing a cut-resistant liner knitted or woven using fibers        selected from Kevlar™, Spectra™, steel wire, or a combination        thereof;    -   c) applying a thermoplastic adhesive, which is solid and        non-tacky at ambient temperature and which comprises a        polyurethane thermoplastic adhesive, to the inner and outer        surfaces of a cut-resistant liner by hot-melt spraying or        dry-powder spraying;    -   d) placing the first shell over a skeletal support;    -   e) dressing the first shell with the adhesive coated liner;    -   f) dressing the first shell with the adhesive-coated liner with        the second shell;    -   g) inflating the first shell placed over the skeletal support        with air pressure to create intimate contact between the first        shell, the adhesive-coated liner, and the second shell;    -   h) subjecting the first shell, the adhesive-coated liner, and        the second shell to infrared radiation, thereby melting the        adhesive and creating a bond between the first shell, the        cut-resistant liner, and the second shell;    -   i) cooling the shells bonded with adhesive layers to create the        cut-resistant, supported polymeric shell article; and    -   j) optionally coating the external surface of the cut-resistant        liner with a flexible polymeric layer.

In the context of the above methods, hot-melt spraying can comprise thesteps of melting the adhesive, delivering the adhesive to a nozzle,which sprays the hot-melt adhesive on either of the polymeric shell orthe liner. The spray pattern can be selected to provide optimal coverageof the shell or liner. Typically, the adhesive used is small, e.g.,about 0.001-0.01 g/cm² or approximately 0.5-5 g per pair of gloves,thereby creating a thin adhesive layer suited for bonding. This smallquantity of hot-melt adhesive applied stays nearly at the same placewhere it was applied during the melting and bonding process, rather thanrunning down complex three-dimensional surfaces of the polymeric shell.Therefore, it is important that the quantity of adhesive used is limitedso as to prevent formation of non-flexible regions in the supportedpolymeric shell article. The adhesive layer is then cooled to ambienttemperature, at which time the adhesive layer is substantiallynon-tacky. This non-tacky property is important for dressing theadhesive-coated component (i.e., shell or liner) with thenon-adhesive-coated component (i.e., liner or shell). A sticky adhesivewill prevent the proper dressing of the adhesive-coated component.

Dry-powder spraying in the context of the above methods can compriseapplying the adhesive as a dry powder at ambient temperature, at whichtime the adhesive is substantially non-tacky. The adhesive-coatedcomponent can then be easily dressed with the non-adhesive-coatedcomponent.

When the article is a glove, a convenient method of bonding anadhesive-coated polymeric shell shaped as a glove is to apply the gloveto a skeleton form, which has metallic rods of small diameter that actas holders for fingers of the glove. The wrist extension of the glove isinserted over a conical section directly below the rod finger supportsand clamped so as to make the glove airtight. The liner is slipped overthe non-sticky adhesive-coated polymeric glove shell. Compressed air ispumped inside the glove, and the glove polymeric shell with the adhesivecoating is inflated until it contacts and is restrained by the liner. Inthis condition, the liner is in contact with the adhesive-coatedpolymeric shell practically everywhere. The inflated glove assembly ismoved to a heating station, which subjects the assembly to a temperaturesufficient to melt the adhesive, i.e., making the adhesive tacky. Aninfrared heat source or a convection heat source can be used in theheating station. The assembly is cooled to ambient temperature, at whichtime the adhesive is securely bonded to the liner and the polymericshell, is non-tacky, and cannot be leached by sweat or degraded by bodytemperature.

Referring to FIG. 1A, there is shown a fragmentary portion of asupported polymeric shell 10, i.e., a finger portion of amoisture-absorbing glove, comprising a polymeric shell 15, a liner 17,and an adhesive layer 16. During processing, the polymeric shell isturned inside-out with the adhesive layer over the outer surface. Theliner is slipped over the non-tacky adhesive layer and heated to meltthe adhesive layer, thereby creating the bond between the polymericshell and the liner. The bond between the polymeric shell, the adhesivelayer, and the liner prevents the excessive stretching of the polymericshell and, therefore, delamination at the interface between thepolymeric shell and the adhesive layer.

Referring to FIG. 1B, there is shown a fragmentary portion of asupported polymeric shell 11, i.e., a finger portion of a cut-resistantglove, comprising a polymeric shell 15, a cut-resistant liner 18, and anadhesive layer 16. During processing, the polymeric shell is turnedinside-out with the adhesive layer over the outer surface. Thecut-resistant liner is slipped over the non-tacky adhesive layer andheated to melt the adhesive layer, thereby creating a bond between thepolymeric shell and the liner. As described above for themoisture-absorbing glove, the bond between the polymeric shell, theadhesive layer, and the liner prevents the excessive stretching of thepolymeric shell and, therefore, delamination at the interface betweenthe polymeric shell and the adhesive layer. In practice, after the bondbetween the cut-resistant liner and the polymeric shell is achieved, theexternal surface of the cut-resistant liner can be coated with aprotective, flexible, polymeric layer, such as polyurethane latex, so asto provide improved product appearance and to protect the cut-resistantfibers from damage.

Referring to FIG. 1C, there is shown a fragmentary portion of asupported polymeric shell 12, i.e., a finger portion of a cut-resistant,moisture-absorbing glove, comprising a polymeric shell 15, amoisture-absorbing, skin-contacting liner 17, adhesive layers 16, and acut-resistant liner 18. During processing, the polymeric shell is turnedinside-out with the adhesive layer over the outer surface. Themoisture-absorbing liner is applied over the adhesive layer and heatedto melt the adhesive layer, thereby creating a bond between thepolymeric shell and the moisture-absorbing liner. Subsequently, thepolymeric shell is turned inside out, a non-tacky adhesive layer isapplied, and then the cut-resistant liner is applied and heated to meltthe adhesive layer, thereby creating a bond between the polymeric shelland the cut-resistant liner. The adhesive-melting step for themoisture-absorbing liner and the cut-resistant liner can be combined. Asdescribed above for the moisture-absorbing glove, the bond between thepolymeric shell, the adhesive layer, and the liners prevents theexcessive stretching of the polymeric shell and, therefore, delaminationat the interface between the polymeric shell and the adhesive layer. Inpractice, after the bond between the cut-resistant liner and thepolymeric shell is achieved, the external surface of the cut-resistantliner can be coated with a protective, flexible, polymeric layer, suchas polyurethane latex, so as to provide improved product appearance andto protect the cut-resistant fibers from damage.

Referring to FIG. 1D, there is shown a fragmentary portion of asupported polymeric shell 14, i.e., a finger portion of a cut-resistantglove, comprising polymeric shells 15 and 18, a cut-resistant liner 17,and adhesive layers 16 and 19. During processing, the polymeric shell iscoated with a non-tacky adhesive layer over the outer surface, and theliner is applied over the adhesive layer. A second polymeric shell isturned inside out, coated with a non-tacky adhesive layer, turned insideout again, and slipped over the liner. Alternatively, the liner can becoated with the non-tacky adhesive layers and slipped over the firstpolymeric shell. Then, the second polymeric shell can be slipped overthe liner. The bond between the polymeric shells and liner by way of theadhesive layers prevents the excessive stretching of the shells anddelamination at the interfaces between the shells and the liner.

Referring to FIG. 2A, there is shown a skeletal support 20 for apolymeric shell. The skeletal support can be used to apply the adhesivelayer over the polymeric shell or to dress an adhesive-coated component.The supports aid in creating a bond between the shell and the liner uponmelting of the adhesive layer. Means are provided to inflate thepolymeric shell so that the adhesive-coated polymeric shell contacts theliner during the melting of the adhesive layer. A skeletal support foran article in the shape of a glove comprises finger supports 25 and athumb support 26 as shown in FIG. 2A. The finger and thumb supports areattached to a wire member 27, which is attached to a tubular member 28.The tubular member 28 is welded to a conical chamber 35 and exits thechamber as shown. The conical chamber 35 has air vent openings at 36 and38 designed to vent the inflating air. The arrows show the airflowwithin the skeletal support. Compressed air is connected to the tubularelement 28 at the bottom of the conical chamber 35 and provides airpressure at the finger support 25 and thumb support 26.

Referring to FIG. 2B, there is shown a front elevational view of askeletal support 20 with an article in the shape of a glove shown indotted lines dressed over the skeletal support. The finger supports 25are inserted into corresponding glove fingers and the thumb support 26is inserted into the glove thumb. The glove covers the conical chamber35. It can be clamped to prevent the displacement of the glove shellwhen air pressure is applied. The clamping means are not shown. Theshell can be coated with a thin adhesive layer, which is solid atambient temperature. The liner is slipped over the adhesive-coatedshell. Alternatively, the inner surface of the liner can be coated withthe adhesive layer and slipped over the shell. Air pressure (arrows) isapplied through the tube 28 welded to the conical chamber 35, andtravels through the central support tube 28, exiting at the fingersupports 25 and thumb support 26. The air pressure inflates thepolymeric shell, and the air is exhausted through the ports 36 and 38.The pressure within the polymeric shell is minimal due to the ventingaction, and the polymeric shell is pressed against the liner with theadhesive layer there between. The assembly is then taken to the heatingstation to melt the adhesive layer.

Referring to FIG. 2C, there is shown a side elevational view 22 of anarticle in the shape of a glove shown in dotted lines 30 dressed over askeletal support. The finger supports 25 are inserted into correspondingglove fingers, and the thumb support 26 is inserted into thecorresponding glove thumb. The glove covers the conical chamber 35. Itcan be clamped to prevent the displacement of the polymeric glove shellwhen air pressure is applied. The clamping means are not shown. Thepolymeric shell can be coated with a thin adhesive layer, which is solidat ambient temperature. The liner is easily slipped over theadhesive-coated polymeric glove shell. Alternatively, the liner can becoated with the adhesive layer and slipped over the shell. Air pressure(arrows) is applied through the tube 28 welded to the conical chamber 35and travels through the central support tube 28, exiting at the fingersupports 25 and the thumb support 26. The air pressure inflates theshell, and the air is exhausted through ports 36 and 38. The pressurewithin the shell is minimal, due to the venting action, and thepolymeric shell is pressed against the liner, with the adhesive layerthere between. The assembly is then taken to the heating station to meltthe adhesive layer.

The present invention provides a supported polymeric shell, which issubstantially free from defects, such as pinholes or cracks, and whichprovides excellent chemical resistance. Since the liner supports thepolymeric shell, it cannot be stretched to degrade the adhesive layerbonding the polymeric shell to the liner. The liner, such as one madefrom cotton and/or rayon, can contact the skin of the user and provideexcellent moisture absorption, i.e., sweat management. Alternatively,the liner, such as one made from steel wire, Kevlar™, and/or Spectra™,can be on the outside of the shell or within the shell and providecut-resistance. The inner surface of such a shell can still comprise amoisture-absorbing liner.

The polymeric shell can be appropriately shaped for a number ofapplications including, but not limited to, a glove, a gauntlet, a boot,an apron and other industrial protective articles, which requirechemical resistance and mechanical integrity. The chemical resistance isprovided by a high quality, pinhole-free, polymeric shell, and thestrength properties are provided by the liner, which is permanentlyattached to the polymeric shell by an adhesive layer.

EXAMPLES

The following examples serve to illustrate the present invention and arenot intended to limit its scope in any way.

Example 1

A nitrile polymeric shell was prepared by conventional dipping in anaqueous latex emulsion, using a coagulant to gel the nitrile latex, andcuring to crosslink the polymer. A layer of thermoplastic polyurethaneadhesive was hot-melt sprayed on the nitrile polymeric shell by sprayingapproximately 3 grams of the adhesive for a pair of gloves. Aconventional knitting process prepared a cotton liner. The liner wasplaced on the adhesive-coated polymeric shell and heated to 125° C.using an infrared heat source. The assembly was cooled. The liner waspermanently bonded to the supporting knitted liner. The supportednitrile polymeric shell was kept in ambient moist air to cure andcross-link the thermoplastic polyurethane adhesive.

Example 2

A strip from Example 1 was cut and evaluated for bond strength. The bondstrength was measured using the test procedure BS EN ISO 2411:200,“Rubber- or Plastics-Coated Fabrics. Determination of Coating Adhesive,”(B.S.I. Chiswick, High Road, London, United Kingdom). The peel strengthwas measured by literally peeling the liner apart from the polymericshell. Each free end of the joined polymeric shell and liner was held inthe jaws of a tensiometer, and opposing forces were applied to peel thetwo apart. The units of measurement are stated in Newton force (N) per50 mm of peel width, that is, N/50 mm width of peel line. The articlewas characterized by a minimum peel strength of 35 N/50 mm width of peelline. More often, the peel strength exceeded 63 N/50 mm in width, andthe peeled sections were characterized by fragmented liner stillattached to the polymeric shell, indicating that the liner providedsupport to the polymeric shell until the supporting liner fragmented.

The subject invention provides a supported polymeric shell characterizedby a combination of properties including:

-   -   a) a pinhole- or defect-free polymeric shell;    -   b) the polymeric shell bonded to a liner using a thermoplastic        adhesive layer placed between the polymeric shell and the liner;    -   c) the adhesive layer being substantially tack-free at ambient        temperature;    -   d) the adhesive layer melting at a temperature below degradation        temperature of the polymeric shell or the liner; and    -   e) the bond between the polymeric shell and the liner achieved        by heating to melt the adhesive layer placed between a liner and        a polymeric shell and cooling the heated supported polymeric        shell,

wherein the bonded liner limits the stretchability of the polymericshell, thereby preventing the separation of the adhesive layer polymericshell interface.

All references, including publications, patent applications, andpatents, cited herein are hereby incorporated by reference to the sameextent as if each reference were individually and specifically indicatedto be incorporated by reference and were set forth in its entiretyherein.

The use of the terms “a,” “an,” “the,” and similar referents in thecontext of describing the invention (especially in the context of thefollowing claims) are to be construed to cover both the singular and theplural, unless otherwise indicated herein or clearly contradicted bycontext. Recitation of ranges of values herein are merely intended toserve as a shorthand method of referring individually to each separatevalue falling within the range, unless otherwise indicated herein, andeach separate value is incorporated into the specification as if it wereindividually recited herein. All methods described herein can beperformed in any suitable order unless otherwise indicated herein orotherwise clearly contradicted by context. The use of any and allexamples, or exemplary language (e.g., “such as”) provided herein, isintended merely to better illuminate the invention and does not pose alimitation on the scope of the invention unless otherwise claimed. Nolanguage in the specification should be construed as indicating anynon-claimed element as essential to the practice of the invention.

Preferred embodiments of this invention are described herein, includingthe best mode known to the inventors for carrying out the invention. Itshould be understood that the illustrated embodiments are exemplaryonly, and should not be taken as limiting the scope of the invention.

1. An article comprising: a) at least one cured, liquid-imperviouspolymeric shell substantially free from defects and in the shape of aglove; b) at least one liner; and c) a non-tacky, thermoplastic adhesivelayer placed between the at least one shell and the at least one liner;wherein the adhesive layer is melted and solidified to create anon-tacky bond between the at least one shell and the at least oneliner, and whereby the liner supports and limits stretchability of theshell, thereby preventing adhesive delamination between the adhesivelayer and either of the at least one shell, the at least one liner, orboth.
 2. The article of claim 1, wherein the liner comprises a woventextile fabric.
 3. The article of claim 1, wherein the liner comprises aknitted textile fabric.
 4. The article of claim 1, wherein the linercomprises a fabric fabricated from cotton, rayon, polyester,polypropylene, Kevlar™, Spectra™, steel wire, or a combination thereof.5. The article of claim 1, wherein the adhesive layer comprises apolymer selected from the group consisting of low molecular weightpolyethylene, polyester, ethyl vinyl acetate, ethylene 2-ethyl hexylacrylate polymer, and polyurethane, and has a melting point of less thanabout 140°C.
 6. The article of claim 1, wherein the adhesive layercomprises a moisture-cure, cross-linking polyurethane.
 7. The article ofclaim 1, wherein the adhesive is applied in the range of about0.001-0.01 gram/cm².
 8. The article of claim 1, wherein the liner hasstretch ability in the range of about 0.5-20%.
 9. The article of claim1, wherein the article is a glove or a gauntlet.
 10. The article ofclaim 1, wherein the liner comprises a cut-resistant liner and thearticle further comprises a second adhesive layer, and amoisture-absorbing liner, wherein the second adhesive layer creates abond between the moisture-absorbing liner and the shell.
 11. The articleof claim 1, wherein the liner comprises a cut-resistant liner.
 12. Thearticle of claim 1, wherein the adhesive layer has a greater stretchability than the at least one liner, and the at least one shell has astretch ability that is greater than or equal to the stretch ability ofthe adhesive layer.
 13. The article of claim 1, wherein the shellcomprises a natural latex composition and/or a synthetic latexcomposition.
 14. The article of claim 13, wherein the synthetic latexcomposition is nitrile latex.
 15. The article of claim 1, wherein thearticle comprises a skin-contacting surface, the liner is on theskin-contacting surface, and the liner absorbs moisture.
 16. Thearticles of claim 15, wherein the liner comprises cotton and/or rayon.17. The article of claim 1, wherein the article comprises anon-skin-contacting surface, the liner is on the non-skin-contactingsurface, and the liner is cut-resistant.
 18. The article of claim 17,wherein the liner comprises steel wire, Kevlar™, Spectra™, or acombination thereof and is optionally encapsulated with a flexible,polymeric coating.